Process monitoring of deep structures with X-ray scatterometry

Abstract

Methods and systems for estimating values of process parameters, structural parameters, or both, based on x-ray scatterometry measurements of high aspect ratio semiconductor structures are presented herein. X-ray scatterometry measurements are performed at one or more steps of a fabrication process flow. The measurements are performed quickly and with sufficient accuracy to enable yield improvement of an on-going semiconductor fabrication process flow. Process corrections are determined based on the measured values of parameters of interest and the corrections are communicated to the process tool to change one or more process control parameters of the process tool. In some examples, measurements are performed while the wafer is being processed to control the on-going fabrication process step. In some examples, X-ray scatterometry measurements are performed after a particular process step and process control parameters are updated for processing of future devices.

What is claimed is: 
     
       1. A method comprising:
 providing an amount of x-ray illumination light directed to a measurement spot including one or more structures partially fabricated on a semiconductor wafer; 
 detecting an amount of x-ray light reflected from or transmitted through the semiconductor wafer in response to the amount of x-ray illumination light; 
 determining values of one or more parameters of interest associated with the partially fabricated one or more structures based on the detected amount of x-ray light; and 
 communicating an indication of the values of the one or more parameters of interest to a fabrication tool that causes the fabrication tool to adjust a value of one or more process control parameters of the fabrication tool, wherein the one or more structures partially fabricated on the semiconductor wafer are fabricated at least in part by the fabrication tool. 
 
     
     
       2. The method of  claim 1 , wherein the amount of x-ray illumination light is provided to the measurement spot and the amount of x-ray light is detected while the fabrication tool is fabricating the one or more structures. 
     
     
       3. The method of  claim 1 , wherein the adjusting of the value of the one or more process control parameters occurs while the fabrication tool is fabricating the one or more structures. 
     
     
       4. The method of  claim 1 , further comprising:
 exposing the semiconductor wafer to a fabrication process environment within a fabrication process chamber during a process interval, wherein the amount of x-ray illumination light is provided to the measurement spot and the amount of x-ray light is detected during the process interval. 
 
     
     
       5. The method of  claim 1 , wherein the amount of x-ray illumination light is provided to the measurement spot and the amount of x-ray light is detected after the fabrication tool has executed a step of a fabrication process flow on the semiconductor wafer. 
     
     
       6. The method of  claim 1 , wherein the values of the one or more parameters of interest are determined at a first process step of a fabrication process flow, and wherein the indication of the values of the one or more parameters of interest communicated to the fabrication tool cause the fabrication tool to adjust a value of one or more process control parameters of the fabrication tool at a second process step subsequent to the first process step in the fabrication process flow. 
     
     
       7. The method of  claim 1 , wherein the values of the one or more parameters of interest are determined at a process step of a fabrication process flow of the one or more structures, and wherein the indication of the values of the one or more parameters of interest communicated to the fabrication tool cause the fabrication tool to adjust a value of one or more process control parameters of the fabrication tool at the process step. 
     
     
       8. The method of  claim 1 , wherein the fabrication tool is any of an etch process tool, a deposition process tool, and a lithography process tool. 
     
     
       9. The method of  claim 1 , wherein the amount of x-ray illumination light is directed to the measurement spot at a plurality of angles of incidence, azimuth angles, or both. 
     
     
       10. The method of  claim 1 , wherein the amount of x-ray illumination light is directed to the measurement spot at a plurality of different energy levels. 
     
     
       11. The method of  claim 1 , wherein the determining the values of the one or more parameters of interest is based on a model-based measurement model, a trained signal response metrology (SRM) measurement model, or a tomographic measurement model. 
     
     
       12. The method of  claim 1 , wherein the one or more structures includes a three-dimensional NAND structure or a dynamic random access memory (DRAM) structure.